钢纤维混凝土焊钉-橡胶连接件受剪承载力试验研究

Experimental study on shear capacity of steel fiber reinforced concrete rubber-sleeved stud shear connector

为建立钢-混凝土组合结构桥梁使用的钢纤维混凝土(SFRC)焊钉-橡胶连接件受剪承载力设计计算方法,设计并制作了18组54个SFRC焊钉-橡胶连接件,通过单调加载与循环加载推出试验,研究了混凝土强度、焊钉直径、钢纤维体积掺量、橡胶套筒高度及厚度、加载模式等对其受剪承载力的影响规律。基于准牛顿法进行非线性拟合,提出了SFRC焊钉-橡胶连接件受剪承载力计算式。研究结果表明:焊钉-橡胶连接件受剪承载力随SFRC强度增大而增加,且增速呈变缓趋势;受剪承载力与焊钉杆截面面积大致呈线性增加关系,而随着橡胶套筒相对截面面积的增大而降低;钢纤维体积掺量不大于0.8%时,其对受剪承载力提升显著,随后增速变缓;加载模式对受剪承载力及破坏模式的影响不大;橡胶套筒可有效降低焊钉抗剪刚度并显著提高其变形性能。所提SFRC焊钉-橡胶连接件受剪承载力计算式可适用于SFRC强度等级CF30~CF60、焊钉直径13~25 mm、钢纤维体积掺量0~1.6%、橡胶套筒厚度不超过焊钉直径的1/2.6的SFRC焊钉-橡胶连接件设计。

To build up a design calculation method for the shear capacity of steel fiber reinforced concrete(SFRC) rubber-sleeved stud shear connectors which were used in composite structure bridge, a large number of push-out tests were carried out under monotonic load and cyclic load. A total of eighteen groups consisting of fifty-four rubber-sleeved stud specimens were designed and fabricated, and the influences of various parameters such as the compressive strength of SFRC, the diameter of rubber-sleeved stud, the volume fraction of steel fiber, the height and thickness of rubber-sleeve and the loading patterns on the shear capacity of SFRC rubber-sleeved stud shear connector were explored. Based on the quasi-Newton method for non-linear fitting technology, the calculation formulas for the shear capacity of SFRC rubber-sleeved stud shear connector were put forward. The results show that the shear capacity of SFRC rubber-sleeved stud shear connector increases with the increase of the compressive strength of SFRC and the growth rate trends to slow down later. The shear capacity approximately linearly increases with the increase of the sectional area of the stud. However, the shear capacity decreases with the increase of the relative sectional area of the rubber-sleeve. When the volume fraction of steel fiber is no more than 0.8%, the shear capacity is significantly improved and then the growth rate slows down after that. The loading patterns have little effect on the shear capacity and failure modes of SFRC rubber-sleeved stud shear connector. The rubber-sleeve can effectively decrease the shear stiffness and significantly improve the deflection behavior of SFRC rubber-sleeved stud shear connector. The proposed design formulas are suitable for the calculation of shear capacity of SFRC rubber-sleeved stud shear connector with compressive strength grade of SFRC ranging from CF30 to CF60, and stud shear connector with a diameter of 13 mm to 25 mm, and stud shear connector with the volume fraction of steel fiber less than 1.6%, and stud shear connector with the thickness of rubber-sleeved no more than 1/2.6 times diameter of the stud connector.